Writing in his column in the Irish Independent, Deignan described how he was involved in an altercation with Rodriguez on the descent of the Puerto del Torno on Sunday, when he was moving up in the peloton to position his Team Sky leader Chris Froome ahead of the final climb.

“As we hurtled along in the rain at around 50kph, Katusha's Spanish team leader Joaquin Rodriguez, who is fourth overall, took umbrage to my presence and nudged me out a little bit. So I held my ground and nudged him back,” Deignan wrote.

“As we continued riding, suddenly, out of the blue, Rodriguez turned towards me and punched me full in the face, splitting my lip and leaving me both stunned and fuming.”

It was a rather unexpected birthday gift for Deignan, who turned 31 on Sunday, but the Donegal man had the restraint not to react to the blow. “Hitting him in such treacherous conditions would only worsen the situation and endanger the riders around us,” he wrote. “As Rodriguez' punch was greeted with a chorus of shouts from the rest of the peloton, I warned him that I'd deal with him off the bike.”

The incident was not noted by the race commissaires after Sunday's stage, nor was it visible in live television pictures.

Deignan admitted that after the stage his immediate desire was to show Rodriguez “what a couple of years training in Letterkenny Boxing Club had taught me” but he ultimately thought better of seeking out a further confrontation.

“As much as I'd have loved to have cornered him in the hotel last night, I knew that nothing good could come of it; either for myself or the team, so when his directeur sportif marched him over to our bus before the start today [Monday] and made him apologise, I swallowed my pride and simply let it go,” Deignan continued.

Contacted by Cyclingnews on Tuesday morning, the Katusha team acknowledged that an altercation had taken place between Rodriguez and Deignan, but said that the contact had been accidental. Katusha added that Rodriguez will offer a full explanation of the incident in his rest day press conference in A Coruña.

“[Rodriguez] made just a gesture with his hand like ‘what are you doing?’ after Deignan hit Purito's handlebars with his handlebars, and he hit Deignan in the face by accident,” a team spokesman said by email. “He apologized and did so in the evening and the morning after. It was not his intention to touch him.”